All of my tanks at least start out level with (metal, not wood) shims if/as required to level the stand. None are on carpets, so crushing is not an issue. One 55 over 33XL in this room is about 1/8th inch off after ~18 years. But it is the house itself, the floor is a bit off now in the room. If it gets any worse I'll correct the tank stand with shims.